3120 hot start issue

[adw]

Absolutley so, however this is only going to help if the throttle is not opening enough on the part throttle lock, you can adjust it yourself. there is also a low speed screw ( it has a fixed main jet ) this can be richened slightly also to help.

[Starscream]

Should have gone to Stihl-savers

[TheHungrySquirrel]

Should have gone to Stihl-savers

 

 

I'm blaming it all on that moody piston stop

[spudulike]

The piston stop - which type? one of those metal ones or the Stihl Plastic type?

It is possible that you have fractured the piston crown and it makes enough compression to start but not enough on a hot start.

 

Had a 262 like that once!

 

I think it needs a look at by a competent tech before getting too down hearted!

[TheHungrySquirrel]

The piston stop - which type? one of those metal ones or the Stihl Plastic type?

 

It is possible that you have fractured the piston crown and it makes enough compression to start but not enough on a hot start.

 

 

 

Had a 262 like that once!

 

 

 

I think it needs a look at by a competent tech before getting too down hearted!

 

 

It was the black plastic stihl one, broke one in my 150 a few days before this happened but managed to get it out.

 

On the 3120 it snapped and popped out the exhaust port and caught the front lip of the piston making a little burr. It was above the rings and had done no damage to pot, I got the pot off and removed the burr, reassembled and now it's doing this.

 

Local dealer seems to keep saying it was flooding.

Would I be able to see the fracture atop the piston or micro size??

[spudulike]

OK, sounds like the piston stop was through the exhaust port rather than between the crown and squish band. Next question - what were you doing and what were you using?

 

Air chuck or tommy bar - and how much force?

 

It is possible that the top ring has become stuck in the ring groove due to the compression of the top edge of the piston, this may cause the issues you have!

 

It is unlikely the port would be damaged with what you have done. Taking the muffler off may give you an idea if the piston has any damage to the front.

[TheHungrySquirrel]

OK, sounds like the piston stop was through the exhaust port rather than between the crown and squish band. Next question - what were you doing and what were you using?

 

 

 

Air chuck or tommy bar - and how much force?

 

 

 

It is possible that the top ring has become stuck in the ring groove due to the compression of the top edge of the piston, this may cause the issues you have!

 

 

 

It is unlikely the port would be damaged with what you have done. Taking the muffler off may give you an idea if the piston has any damage to the front.

 

 

Yep it had popped into the exhaust outlet.

Was trying to change the sprocket and it was a stihl piston stop that I have had a similar problem with on another saw.

 

Just my arms and a bar spanner to undo it so nothing to aggressive.

 

No visible damage to rings or piston.

 

Update: I took it to my local dealer who had it for a week and then told me it was just flooded but handed me a £40 bill for new plug, fuel and labour. It hasn't cured the problem though and now there demanding payment.

Surely should be covered under warranty as saws less than a year old and has about 2-3 hours run time total.

[spudulike]

Take the saw back to the dealer and ask him to start it and you will pay the bill if it fires and runs! Either you have some sort of starting issue or they haven't fixed the issue!

 

The warranty thing - if the issue was caused by the piston stop breaking then it is your fault. If the issue has been there since day one or has some sort of manufacturing fault then it is a warranty issue, difficult to tell at the moment.

 

I would pull the spark plug out, turn the saw upside down and pull the start handle over fast 3-5 times and see how much fuel comes out of the plug hole. Light vapour is fine but if it splatters and drips out then it is flooded.

 

If it is flooded, pull it over hard a few more times, let it dry overnight with the plug out, heat the plug up with a plumbers torch or gas hob and then put it back, use the fast idle and full choke and pull it over hard 3-4 times and then knock the choke off and give yourself a work out - should fire or pop/run.

 

If it doesn't - back to the dealer or find another route to fix it.

[TheHungrySquirrel]

Cheers for that advice spud. I'll have a play with it tomorrow.

The issue is starting it once hot, used it to stump some beech trees the other day made like 4 cuts then turned it off and couldn't start it all day.

[spudulike]

Cheers for that advice spud. I'll have a play with it tomorrow.

The issue is starting it once hot, used it to stump some beech trees the other day made like 4 cuts then turned it off and couldn't start it all day.

 

Sounds like it is possible that the saw is lacking compression but is difficult to measure on these big saws. I still wonder if the top ring has stuck in the groove after the piston stop episode!